- Now, because deer can't eat them, they've come to overwhelm nearly all their natural competitors. They are among the few successful survivors of a devastating plague of deer.
- "The whole eastern US has been over-browsed for many decades,"
- Pennsylvania is the state most severely affected by the problem, which began in the early 20th century, when wolves and cougars had been hunted to extinction in the east.
- So the Pennsylvania Game Commission brought in deer from Virginia and Wisconsin and put a moratorium on hunting those without antlers.
- At the same time, forests across much of the Northeast were being clear-cut, a process that in Pennsylvania was completed by the mid-1930s. As any deer hunter knows, deer love a clear-cut.
- The new shrubs and grass that spring up in forest openings provide abundant browse.
- The deer population skyrocketed, and although limited hunting focused on bucks was reinstated, by the 1940s deer were radically changing eastern forests.
- The hay-scented fern, for example, once covered less than 3 percent of the forest floor. Now, because it thrives in clear-cuts and deer devour its competitors, it dominates more than a third of the forested area in Pennsylvania and is abundant throughout much of the northeastern United States.
- Across more than half of the ANF, a carpet of hay-scented fern suppresses the growth of other native herbs and of tree seedlings in the understory.
- "If all the deer disappeared tomorrow," says Carson, "that dense layer of fern would continue to suppress the growth of new trees."
- A similar pattern of logging and overbrowsing is affecting forests from New Zealand to Europe to North America.
- Some Pennsylvania clear-cuts where thick growths of fern and grass have taken hold remain empty of new trees 80 years after they were logged.
- Understory plants are also hard hit. In a study published in Sciencein February 2005, James McGraw and Mary Ann Furedi of West Virginia University found that wild ginseng, a native herb that has long been collected for export to Asia, is being decimated by deer.
- Ginseng populations and individual plants have grown progressively smaller over the last century, and the harvest has shrunk by a factor of three or four since the 1800s.
- identify plants that had been browsed: They showed a distinctive tear on the stem, and telltale deer tracks or scat were often nearby. A browsed plant won't regrow until the following year, and it will come back smaller, producing fewer flowers and seeds.
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